Coaxial Cable in Computer Networks

What is Coaxial Cable?

An electrical cable with copper as a conductor material, a shielding of insulator material, and a braided mesh metal is known as a coaxial cable in computer networks. A coaxial cable is also known as a coax in short form. The coaxial cable was designed by Oliver Heaviside in the year 1880. He was an English engineer and mathematician.

As we know, the conductor helps to transfer charges, the insulator is used for protection in normal wires and cables. Here, we have a braided mesh of metal as well which helps to prevent cross-talk and signal interference. We will be learning more about the structure of the coaxial cable in the next section.

The copper conducting material used in the coaxial cable is capable of transmitting signals over distances and the insulating material provides insulation to the copper material so that the data does not get lost in the surrounding medium. The insulating material is itself covered or coated by the mesh metal material which helps to prevent cross-talk and signal interference in the electrical signals. There is even more protection present in the coaxial cables. We have protective plastic layer protection above all for some extra safety for the cable.

The coaxial cable supports high-speed signal transfer over a larger distance as compared to other cables like twisted pair cables. We can even pass or transfer the Radio Frequency (RF) using the coaxial cable in the form of a transverse electromagnetic wave. We mainly use the coaxial cables in the transmitting lines and when we have to pass high-frequency signals we want very low loss.

We can divide the coaxial cables into two broader categories namely-

1. BaseBand: Used in transmitting single signals at a time at a very high speed. It is widely used in LANs. We use 50-ohm coaxial cables for digital transmission. In the BaseBand coaxial cables, we need to amplify the signal every 1000 feet which is one of the drawbacks of the BaseBand coaxial cables.
2. BroadBand: As we have discussed the BaseBand cables are used for digital transmission, and the Broadband cables are used to transmit the analog signals using the standard cable TV cable. We can even transmit multiple signals simultaneously at a very high speed. The BroadBand cables cover a larger area of signal transmission as compared to the BaseBand coaxial cables.

Structure of Coaxial Cable

Let us now learn about the parts or structure of the coaxial cable in detail.

Let us first look at the image or the diagram of the coaxial cable so that things can become clearer to us.

So, the coaxial cable in computer networks has four parts namely-

1. Conductor: The conductor is the central stiff component in the coaxial cable and it is made up of copper material. Its main work is to transfer the data in the form of electrical signals.
2. Insulator: The insulator is coated over the copper conductor which protects the copper wire. It is made up of dielectric plastic material and its main work is to maintain a space between the mesh shield and the copper material.
3. Braided Mesh Metal: After the insulator, we have a braided mesh of copper material that helps us to shield the electrical signal from electromagnetic interference. This braided mesh material is woven. Since the electromagnetic induction can pass into and out of the coaxial cables so the braided mesh material also helps us to shield the coaxial cables from the EMI.
4. Protective Plastic Layer: Finally to protect the conductor, insulator, and mesh metal, we have another coating of the plastic layer. The main aim of this layer is to protect the internal layers from damage. It is very lightweight.

Types of Coaxial cables

We have several types of coaxial cables used according to the type of construction of the coaxial cables. Let us learn about the various types of coaxial cables.

Hard Line Coaxial Cable

A coaxial cable whose center material i.e. the conductor is made up of copper, aluminum, steel, and silver is known as hardline coaxial cable. The diameter of the hard-line coaxial cable is comparatively larger than the other types of coaxial cables. We mainly use hardline coaxial cables for high-signal-strength applications. The thickness of this cable is around 0.5″ to 1.75". We can also see the hard-line coaxial cables being highly used in the field of cable TV channels as well as in internet cabling and telephone cabling.

Triaxial Cable

A coaxial cable that has an additional copper braid mesh added to the normal coaxial cable is known as a triaxial cable. The triaxial cable is also known as Triax. This additional copper braided mesh provides an extra shield which helps in protection from external noise. The triaxial cable also provides more bandwidth than other coaxial cables. We can see the Triaxial coaxial cables being highly used in the field of television production for making the connection between the cable and the camera control unit. It can also detect and measure low currents.

Flexible Coaxial Cable

As the name suggests, a flexible coaxial cable is quite flexible compared to other coaxial cables. The inner material over the conductor is made of a flexible polymer, making it more flexible. In a flexible coaxial cable, we have a protective external jacket. We can see flexible coaxial cables being highly used in domestic applications such as cable TV equipment or home video equipment.

Semi-Rigid Coaxial Cable

As the name suggests, a semi-rigid coaxial cable is moderately rigid as compared to other coaxial cables. The inner material over the conductor is made up of dielectric polytetrafluoroethylene which makes it semi-rigid. It is mostly used as semi-rigid assemblies for test equipment, aerospace, wireless, medical, and low PIM applications.

Formable Coaxial Cable

The formable coaxial cable can be treated as an alternative to the formable coaxial cable. It is also semi-rigid but in this cable, we have a rigid copper outer sheath instead of a flexible metal sheath for better utilization.

Rigid Coaxial Cable

A rigid coaxial cable is comprised of two tubes of copper. Both of the copper tubes are supported at the ends of the cable ends and there is a fixed interval across the entire length of the cable. For the interval, we use the PTFE supports or disk insulators. Since it is a rigid cable, we cannot bend down the coaxial cable. The main use case of the rigid coaxial cable is in the field of TV broadcasting systems and FM broadcasting systems.

Twinaxial Cable

The twin-axial cable has a twin or two central conductors present inside the core. For the outer material, we have a single core made up of dielectric. the twin axial cable is mainly used for low-frequency digital transmission and video transmission.

RG-6 Coaxial Cable

The RG-6 coaxial cable or Radio Guide 6 frequency cable is used in cable TV and internet lining systems in broadband. Here $6$ represents the diameter i.e. $0.06$". The RG-6 cable is also known as the RF cable. Since the RG-6 cable has a large conductor which helps to provide improved signal quality. These features make the RG-6 coaxial cable more popular. Some of the RG-6 coaxial cables are made waterproof and are also used in the ceiling and walls.

RG-8 Coaxial Cable

The RG-8 coaxial cable or Radio Guide 8 frequency cable is used in thick ethernet. It is widely used in carrying radio transmission signals. Some of the use cases of the RG-8 cable are audio control rooms, radio stations, external radio antenna connections, etc.

RG-9 Coaxial Cable

The RG-9 coaxial cable or Radio Guide 9 frequency cable is used in thick ethernet. The RG-9 coaxial cable is made up of a silver-coated copper conductor having the protection of Polyethylene (PE) dielectric. The working range of the RG-9 cable is from -40°C to 80°C.

RG-11 Coaxial Cable

The RG-11 coaxial cable or Radio Guide 11 frequency cable is used in thick ethernet. The RG-11 coaxial cable is somewhat similar to the RG-6 and RG-59 coaxial cables. The RG-11 coaxial cables are longer lasting as compared to other RG series. It is thicker as compared to the RG-6 cable and has an impedance of 75 ohm which helps in delivering a higher signal to the receiver. As it is thicker than the RG-6 cable which makes it less flexible but the loss rate of signals is also lower. Some of the use cases of the RG-11 coaxial cable are satellite, TV, cable TV, and HDTV connections.

RG-58 Coaxial Cable

The RG-58 is a lightweight coaxial cable that is mainly used in lower-frequency signals and RF connections. The impedance range of the RG-58 cable is from 50 ohms to 52 ohms. The RG-58 coaxial cable is one of the smallest and slimmest of the coaxial cables. Some of the use cases of the RG-58 coaxial cable are radio communications, thin Ethernet networks, and mobile installations.

RG-59 Coaxial Cable

The RG-59 coaxial cable can also be compared with the RG-6 coaxial cables but it has a thinner central conductor compared to the RG-6 cable. With the help of RG-59 coaxial cable, we can transmit the low-frequency transmission more efficiently in shorter runs. Some of the use cases of the RG-59 coaxial cable are Cable TV, satellite boxes, and CCTV systems.

Coaxial Cable Connectors

We use the coaxial connectors to connect the coaxial cable with devices. One of the most common coaxial cable connectors is barrel connector. Baller connector has become so famous due to their unique shape. We have one more type of widely used connector named the Bayonet Neill-Concelman (BNC) connector, this connector can be pushed and locked into place with only a half turn.

Apart from the above two, other barrel-type coaxial cable connectors either use a screw (this requires some effort to install) or a push mechanism i.e. push to lock the cable (it is less secure). The BNC connector can also be divided into three types:

1. BNC Connector
2. BNC T-Connector
3. BNC Terminator

Please refer to the image provided below to see the various types of coaxial cable connectors.

Let us see some of the properties of the coaxial cable connectors.

1. We use the BNC connector to connect the end of the cable to a device. For example to connect a cable to the TV set.
2. We can use the BNC-T connector to connect the ethernet network to computer devices or other devices.
3. BNC Terminator is used to prevent any kind of reflection of the signal. So, we use it at the endpoint of the table before connecting.

General Properties of Coaxial Cable

Let us now learn some of the properties of coaxial cables that make them so useful.

• It provides high bandwidth, and hence we can transmit signals at a higher data rate. The coaxial cable has a thicker gauge which increases the available bandwidth and hence increases the transmission distance.
• A coaxial cable contains a single, two-conductor wire and has an outer shield. The shield may also have a braided covering and a plastic covering.
• We can use the BALUN (Balanced/Unbalanced) connector to increase the connectivity of a coaxial cable.
• It has a very significant bandwidth as compared to other cables. This feature makes it highly usable in high-capacity applications like data transmission and image transmission.
• Due to the presence of the outer shielding, the performance of the coaxial cable is exceptionally good. The outer shielding also avoids data loss.
• It is inherently more secure than other cables like twisted pair cables, etc.

Applications of Coaxial Cable

So far we have discussed a lot about coaxial cable in computer networks, let us now learn about the various applications of coaxial cables.

1. Coaxial cables are widely used in Television. The resistance of the coaxial cable used in television is 75 ohms. We can use the RG-6 coaxial cable in televisions.
2. Coaxial cables are used on the internet for carrying electrical signals over the network. We can also use the RG-6 coaxial cable in case of internet.
3. Coaxial cables are also used in CCTV systems. We can use the RG-6 and RG-59 cables for the CCTV camera systems.
4. HDTV uses RG-11 coaxial cables because the RG-11 coaxial cables provide more space for better signal transfer.
5. For the video transmission, we can also use coaxial cables. We use the RG-6 coaxial cables as it provides better digital signals than other coaxial cables. We can also use the RG-59 coaxial cables for lossless video signal transmission.

Some other applications of coaxial cables are:

• Analog telephone networks use coaxial cables.
• In digital telephone networks.
• In LANs and MANs (traditional ethernet-based).

Advantages of Coaxial cable

Let us now learn about the various advantages of coaxial cables.

• The coaxial cables can be used to deal with both analog signals as well as digital signals.
• The coaxial cables offer high bandwidth as compared to other data transmission cables such as twisted pair cables.
• We can transfer data up to larger distances using coaxial cables.
• It is less expensive than optical fibers.
• It provides lower error rates than twisted pair cables.
• We cannot tap a coaxial cable easily as a coaxial cable is covered with plastic jackets.
• Coaxial cables are easy to install. Coaxial cables are also more scalable.
• In coaxial cables, the data transmission is distortionless. Coaxial cables also provide better protection from noise.

Disadvantages of Coaxial cable

Let us now learn about the various disadvantages of coaxial cables.

• Coaxial cables are more costly than twisted pair cables.
• Coaxial cables can be easily damaged due to a lightning strike.
• These cables can transmit the data over a smaller distance as compared to optic cables.
• The bandwidth of a coaxial cable is lesser than fiber optic cable and twisted-pair cable.
• The failure of a single cable may fail the entire network.
• We need to ground the coaxial cables so that crosstalk can be prevented.
• The coaxial cable is very bulky as it contains several layers.
• A hacker can hack the coaxial cable by attaching a T-joint present in the coaxial cable. Hence, there is a question about the security of the data.

Coaxial Cable vs. Fiber Optic Cable

Let us now learn about some of the differences between coaxial cables and fiber optic cables.

• In coaxial cables, we have larger signal loss as compared to a fiber optic cable.
• We should use coaxial cables for shorter distances but a fiber optic cable can be used for both small distances as well as larger distances.
• Fiber optic cables are costlier than coaxial cables.
• Fiber optic cables can carry far more information than coaxial cables.
• Fiber optic cables are not often in residential and consumer settings than coaxial cables.
• The coaxial cables are easy to install and more durable than the fiber optic cables.
• The fiber optic cables provide faster data transfer rates than the coaxial cables.